Step 1: Get prospecting

To mine an asteroid, a company like Planetary Resources first has to find one that promises a good return on investment. But asteroids don't glitter like stars. They are small, dark, and easily obscured by the distorting effect of Earth's atmosphere. The best way to hunt for them is with a telescope floating in space. At the Bellevue, Wash., headquarters of Planetary Resources, chief engineer and company president Chris Lewicki is assembling the components of the first privately owned space telescope, the Arkyd 100 series.

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The 44-pound spacecraft will be smaller and simpler than any government-funded space telescope. The $1.5 billion Hubble Space Telescope has a 94-inch-diameter primary mirror; Arkyd's mirrors will be 9 inches wide. Hubble has a wide field of view, as well as other instruments to scan objects in distant space. Arkyd needs only to look in our own solar system for targets. Being small saves money: Rockets carrying larger sats could also haul these telescopes as secondary payloads, decreasing launch costs.

Space sells, but who's buying?

Planetary Resources plans to build a fleet of space telescopes to help drive the per-unit cost down to less than $10 million. Having multiple telescopes is insurance in case one fails. "We need to make something in an assembly line," says Lewicki, a former Jet Propulsion Laboratory Mars mission manager. "We can't just build one precious jewel that we treat with kid gloves."

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The Planetary Resources team will also rent out the Arkyd 100s, the company's first stab at making money. Its space telescopes can be used by cosmic researchers or by Earth scientists who want to examine the planet from space at a resolution of about 6 feet per pixel. Planetary Resources hopes to launch the first satellite by the end of 2013; company officials say rental prices have not yet been determined.

A NASA engineer stands in front of six segments of the James Webb Space Telescope's primary mirror. Space miners may field the first privately owned space telescopes—and rent them out.

Step 2: Assay and stake a claim

Once company telescopes spot a mining prospect, there's only one way to determine what resources the asteroid contains: Get close.

The Planetary Resources team envisions a swarm of prospecting bots heading out to conduct close flybys of near-Earth asteroids (NEAs). "We're talking about building interplanetary probes at a fraction of the cost [of current models], which requires doing things very differently," Diamandis says. NASA has used this form of propulsion twice for deep-space exploration. It uses electricity to positively charge xenon atoms, which are pulled out of the craft by magnets. The repulsive force provides thrust that propels a vessel, building speed over the course of years. It takes a while, but when it gets going the craft can exceed 200,000 mph.

The asteroids of interest likely will be less than 1 mile in diameter, too small to have appreciable gravity. Spacecraft don't land on such small asteroids; they dock to them. A spacecraft will slowly approach, getting close enough to barely touch the asteroid's surface before deploying an anchor. Grappling hooks might just grab a chunk of surface material and float away. A better option is to deploy drills in each landing pad that secure the craft to the surface.

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"We're talking about building interplanetary probes at a fraction of the cost."

The robot would then analyze the water and metal content of the asteroid and beam the results to Earth. The tool of choice for this assay would be a laser-induced breakdown spectroscopy system, or LIBS. Lasers vaporize surface material so sensors can analyze the light emitted by the resulting plasma to identify elements. The first LIBS to be deployed to another world, ChemCam, is currently en route to Mars aboard NASA's Curiosity rover.

The prospecting craft might also tag the asteroid by planting a radio beacon on its surface. According to company officials, the beacon would do more than help future missions get a fix on an asteroid's location. "Placing a beacon is part of building a case for ownership," Diamandis says.

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A private company's claim to an asteroid is uncharted legal territory. In the next decade lawyers may have to factor in the presence of private-sector entrepreneurs in the Outer Space Treaty, first signed in 1967 and ratified by more than 100 nations. If it turns out that possession really is nine-tenths of the law, then a simple radio transmitter could help make the miner's case.

Step 3: Start digging

Space miners will prize water more than gold. Its value manifests when it is split into its elements: Hydrogen can recharge power cells and be recombined with oxygen to produce energy-rich fuel. Harvesting water in space is cheaper than shipping it from Earth. Every gallon, at a weight of 8.33 pounds, can cost tens of thousands of dollars to launch. Planetary Resources could profit by selling space-harvested water to governmental or private spacecraft at a premium but for less than it would cost to deliver from Earth.

Carbonaceous chondrite asteroids are the best prospects for water. The surface of these so-called C-type asteroids is crumbly, says John Lewis, professor emeritus at the University of Arizona and author of Mining the Sky, the seminal book on the space industry. "You can hold a cube between your thumb and your forefinger and crush it," he says. There's no need to burrow; you can just scrape the surface of a C-type asteroid to mine its water.

A swarm of mining bots, clinging with barbed feet to the surface of an asteroid, would slurp up water-laden soil through proboscis-like drills, while others would vacuum the debris left in their wakes. The robot would then pull out the soil, or regolith, and deposit it in a sealed container. The robot would walk, float, or crawl to a processor lashed to the surface or floating above it. The processor would heat the regolith to release water vapor, which would be collected into a storage tank.

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Space miners face a more difficult challenge when harvesting metal. M-type asteroids, essentially big flying chunks of solid metal, might not feasibly be mined, says Harry McSween, geoscientist at the University of Tennessee and chair of the surface composition group for NASA's Dawn asteroid probe. Anchoring to such a body would be hard enough—drill-style landing pads wouldn't work—let alone sawing off a chunk of the asteroid for processing. "When you think about how much energy would be required, it seems pretty unrealistic," McSween says.

"You can hold a cube between your thumb and your forefinger and crush it"

But Lewis figures that some asteroids might be made up of as much as 30 percent metal, in the form of an iron-nickel-cobalt and platinum-group alloy. "The temptation is to simply use a magnet to pluck the metal grains out of that regolith," he says.

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Some metal-rich asteroids might be worth taking closer to Earth, as close as the moon, in their entirety. "The concentration of metal is so high that you have to wonder whether you could just bring the whole thing back," Lewis says.

Step 4: Deliver the goods

Space sells, but who's buying?

It remains unclear who will purchase the goods that space miners have gone to such pains to gather.

The most lucrative opportunity might be platinum-group metals—one category of the few space commodities that would be shipped back to Earth. "These materials enable so many different high-tech processes that we use," Lewicki says. Today, platinum-group metals are essential to catalytic converters in petroleum engines, as catalysts in the production of silicone, and in the manufacturing of glass. They are incorporated into hard drives; in spark plugs, where their low corrosion rates allow 100,000-mile life spans; and in medical devices, where they are prized for their biocompatibility.

A 500-ton asteroid with 0.0015 percent platinum metals—a common percentage—would have three times the richest concentration found on Earth. "To have more of this material will open up economies that we can't even predict," Lewicki says.

But most asteroid commodities will only be marketable in a future where ambitious spaceflight is a regular human activity; for example, extraterrestrial depots where spacefarers could top off their fuel tanks and water supplies while on long trips. If there are no such trips, there is no business model.

Similarly, the idea that common metals will be useful in space is predicated on a manufacturing industry that is building space stations and spacecraft in orbit. Assembling structures in space, rather than launching them from Earth, is appealing because it avoids the cost of launch. A lack of orbital construction or the advent of cheaper launch systems could obviate this business.

If space stations are growing food for full-time residents, they could become lucrative markets for more than iron and steel. Asteroid-derived nitrogen and ammonia would be in demand for fertilizer. Such industries are vital if humans are to make their home in space. "We're talking about technologies that break the umbilical cord to Earth," Lewis says.

Planetary Resources' scheme is more than a business plan, it's a rose-colored blueprint for supporting space exploration. Its existence speaks to humanity's drive to explore, to spread, and to support the most audacious of our dreams.

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